Global Warming revisited
Roger Harrabin, the BBC Environment Analyst reports.
Global temperatures this year will be lower than in 2007 due to the cooling effect of the La Nina current in the Pacific, UN meteorologists have said. The World Meteorological Organisation's secretary-general, Michel Jarraud, told the BBC it was likely that La Nina would continue into the summer.
This would mean global temperatures have not risen since 1998, prompting some to question climate change theory. But experts have also forecast a record high temperature within five years.
In the meantime the AP reports that cosmic rays play no role in global warming. "Physicist Terry Sloan of Lancaster University and Arnold Wolfendale of Durham University said their research finds no evidence of a link between the ionizing cosmic rays and the production of low cloud cover."
"This is of vast significance because if the skeptics are right, it would mean we're wasting our time trying to cut greenhouse gases," the researchers said in a statement. "But we couldn't find the link they were proposing which means we are right to be cutting carbon emissions."
The cosmic ray theory was developed by Danish scientist Henrik Svensmark at the Danish National Space Centre and featured in a controversial British documentary, "The Great Global Warming Swindle." Svensmark suggested that when the solar wind is strong, the planet warms up because fewer clouds are produced and more of the sun's heat reaches the surface.
Svensmark's claims that solar-driven cloud formations affect earth temperatures more than carbon emissions disturbed the global warming orthodoxy. However, it is unclear whether the Durham University study disproves Svensmark's claim at all.
Later in 2007, Svensmark and Friis-Christensen brought out a Reply to Lockwood and Fröhlich which concludes that surface air temperature records used by Lockwood and Fröhlich apparently are a poor guide to Sun-driven physical processes, but tropospheric air temperature records do show an impressive negative correlation between cosmic-ray flux and air temperatures up to 2006 if a warming trend, oceanic oscillations and volcanism are removed from the temperature data. They also point out that Lockwood and Fröhlich present their data by using running means of around 10 years, which creates the illusion of a continued temperature rise, whereas all unsmoothed data point to a flattening of the temperature, coincident with the present maxing out of the magnetic activity of the Sun, and which the continued rapid increase in CO2 concentrations seemingly has been unable to overrule. This reply has so far not been published in a peer-reviewed journal.
This blog is not the place to discuss scientific controversies. But it may be pertinent to point out that a combination of recent lower temperatures and questions posed by serious scientists have returned the climate change debate to the realm of science once more. And this can only be good. The study of climate is above all a scientific question, not a political one.
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